1. Field of the Invention
The invention relates to a cassette handling apparatus for recording and/or playback of signals on magnetic tape contained in a cassette (hereinafter referred to simply as a cassette recorder); and more particular to a cassette recorder having a magnetic head unit which is movable with respect to the housing between an operating position and a retracted position, the latter allowing insertion or removal of a cassette; and a cassette support adapted to position the cassette in a direction transverse to the direction of tape transport past the head, in the plane of the tape.
The most widely used type of magnetic tape cassette for quality reproduction has two hubs placed side-by-side with the magnetic tape wound around and passing between them. One particular design of cassette of this general type has come into predominant use for entertainment purposes, and is also used in some dictation applications. This cassette, which is depicted for example in U.S. Pat. No. 3,396,899 is commonly called the "Compact Cassette." Although it can be manufactured relatively inexpensively, it has a fairly rigid housing structure which permits good alignment of the tape with regard to the outer surfaces of the flat housing in which the tape and two hubs are contained. The tape passes an opening in a long or front wall of the housing, through which opening the magnetic heads are inserted to engage the tape and a pressure roller is inserted to press the tape against a capstan that extends up through a hole in the bottom wall of the cassette. Drive spindles for the two hubs also project up through openings in the bottom wall of the cassette. Thus in order to locate the cassette on a playing apparatus, there must be motion with respect to operational parts of the apparatus in two directions, first to pass the spindles and capstan through their openings into position, and then transversely so that the heads and pressure roller may engage the tape.
Tape cassettes for audio entertainment use were originally intended for low priced magnetic tape equipment, whose performance was less than that of the so-called reel-to-reel recorders. However, because the separate magnetic tape reels of the reel-to-reel machines could not be placed on the apparatus in a single motion, the development of the magnetic tape cassette was intended to make magnetic tape equipment more popular and available at a lower price. Moreover, because of the suitability of the cassette recorders for portable use, more early cassette recorders had inexpensive electronic components and circuits and small loudspeakers that could not provide audio performance equivalent to the higher rated equipment. Although recently cassette recorders are now produced for the higher price and performance ranges, and maintain the desirable convenience of handling and in some cases may comply with hi-fi standards, as a product the small portable cassette recorder is still eminently suited for the lower price range in which the cost of materials and assembly time become very important.
2. Description of the Prior Art
In order to position the compact cassette or similar cassettes sufficiently accurately in a tape apparatus, so that the head will have proper engagement with the narrow track of information recorded along the tape, known tape deck mechanisms have made extensive use of metal components, such as a metal base plate and a metal head holder. Because of weight and cost considerations, portable cassette recorders almost always use a plastic housing; more recently, in order to reduce cost tape deck mechanisms making considerable use of plastic materials and parts have been introduced, and some units have been proposed which would even use a plastic head holder. However, in general this construction has involved the replacement of metal parts by plastic parts, so that in effect the conventional metal deck mechanisms have been "translated" into plastic (for example, British patent specification No. 1,401,740).
The known plastic mechanisms have used plastics of good availability and low price, which plastics unfortunately have a lower strength, a much lower modulus of elasticity, a greater temperature dependence of the modulus of elasticity, and much lower dimensional stability than the metal parts that are replaced. Successful production of a good quality recorder with plastic parts in place of metal has required comparatively expensive, stable plastics, which could only be processed by those manufacturers having great experience in the field of plastics.
Although it has been recognized that in the use of a plastic deck mechanism, accurate relative positioning of the magnetic heads, capstan and pressure roller is required for accurate transport of the comparatively narrow magnetic tape, achieving this goal using part designs which are the same as that of the previous metal parts has made it difficult to provide a recorder whose reproduced sound meets reasonable quality standards with a high reliability of long operating life. Moreover, inability to guide the tape accurately can damage the tape in the cassette, and in some cases may even render the tape cassette completely useless.
Another facet of cassette recorder design has revolved around the convenience of handling. Particularly suited for use in automobiles, cassette recorders such as that described in U.S. Pat. No. 3,747,941 do not require manual actuation of a "Play" button in order to move the magnetic head unit into the operating position and to energize the transport drive motor and the electronic circuitry. This has been particularly advantageous where operation should demand a minimum of attention from the user, for example the automobile driver. In such a recorder a spring or other device will bias the head holder towards its operating position; and an actuating means is provided for manually moving the head holder against the action of the previously mentioned spring from the operating to a more retracted position, in which a locking means will lock the head holder so retracted. The locking means and unlocking means utilize a second spring or resilient device and a movable unlocking member biased by the second spring, the unlocking member being affected by the exertion of manual pressure on the cassette.
In a previously known cassette recorder of this general type, the locking means utilizes a small pin which projects upward through the base of the apparatus. After placing the cassette on the apparatus, pressure is exerted on the front of the cassette, that is, the edge near the magnetic heads, and the head holder is released from its locked position and is moved to the operating position by the first spring. To turn off the equipment, manual pressure on two interlocked push buttons disposed one to each side of the apparatus is required, so that the head holder is returned to its more retracted position and at the same time the pin moves upward thereby pushing the cassette up.